//recorder.js
export default class Recorder {
	constructor(stream, config) {
		//兼容
		window.URL = window.URL || window.webkitURL;
		navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;

		config = config || {};
		config.sampleBits = config.sampleBits || 16;   //采样数位 8, 16
		config.sampleRate = config.sampleRate || 8000; //采样率(1/6 44100)

		this.context = new (window.webkitAudioContext || window.AudioContext)();
		this.audioInput = this.context.createMediaStreamSource(stream);
		this.createScript = this.context.createScriptProcessor || this.context.createJavaScriptNode;
		this.recorder = this.createScript.apply(this.context, [4096, 1, 1]);

		this.audioData = {
			size: 0,          //录音文件长度
			buffer: [],    //录音缓存
			duration: 0,   // 录音时长
			inputSampleRate: this.context.sampleRate,   //输入采样率
			inputSampleBits: 16,     //输入采样数位 8, 16
			outputSampleRate: config.sampleRate,   //输出采样率
			oututSampleBits: config.sampleBits,       //输出采样数位 8, 16
			input: function (data) {
				this.buffer.push(new Float32Array(data));
				this.size += data.length;
				this.duration += 4096 / this.inputSampleRate;
			},
			compress: function () { //合并压缩
				//合并
				let data = new Float32Array(this.size);
				let offset = 0;
				for (let i = 0; i < this.buffer.length; i++) {
					data.set(this.buffer[i], offset);
					offset += this.buffer[i].length;
				}
				//压缩
				let compression = parseInt(this.inputSampleRate / this.outputSampleRate);
				let length = data.length / compression;
				let result = new Float32Array(length);
				let index = 0, j = 0;
				while (index < length) {
					result[index] = data[j];
					j += compression;
					index++;
				}
				return result;
			},
			encodeWAV: function () {
				let sampleRate = Math.min(this.inputSampleRate, this.outputSampleRate);
				let sampleBits = Math.min(this.inputSampleBits, this.oututSampleBits);
				let bytes = this.compress();
				let dataLength = bytes.length * (sampleBits / 8);
				let buffer = new ArrayBuffer(44 + dataLength);
				let data = new DataView(buffer);

				let channelCount = 1;//单声道
				let offset = 0;

				let writeString = function (str) {
					for (let i = 0; i < str.length; i++) {
						data.setUint8(offset + i, str.charCodeAt(i));
					}
				};

				// 资源交换文件标识符
				writeString('RIFF');
				offset += 4;
				// 下个地址开始到文件尾总字节数,即文件大小-8
				data.setUint32(offset, 36 + dataLength, true);
				offset += 4;
				// WAV文件标志
				writeString('WAVE');
				offset += 4;
				// 波形格式标志
				writeString('fmt ');
				offset += 4;
				// 过滤字节,一般为 0x10 = 16
				data.setUint32(offset, 16, true);
				offset += 4;
				// 格式类别 (PCM形式采样数据)
				data.setUint16(offset, 1, true);
				offset += 2;
				// 通道数
				data.setUint16(offset, channelCount, true);
				offset += 2;
				// 采样率,每秒样本数,表示每个通道的播放速度
				data.setUint32(offset, sampleRate, true);
				offset += 4;
				// 波形数据传输率 (每秒平均字节数) 单声道×每秒数据位数×每样本数据位/8
				data.setUint32(offset, channelCount * sampleRate * (sampleBits / 8), true);
				offset += 4;
				// 快数据调整数 采样一次占用字节数 单声道×每样本的数据位数/8
				data.setUint16(offset, channelCount * (sampleBits / 8), true);
				offset += 2;
				// 每样本数据位数
				data.setUint16(offset, sampleBits, true);
				offset += 2;
				// 数据标识符
				writeString('data');
				offset += 4;
				// 采样数据总数,即数据总大小-44
				data.setUint32(offset, dataLength, true);
				offset += 4;
				// 写入采样数据
				if (sampleBits === 8) {
					for (let i = 0; i < bytes.length; i++, offset++) {
						let s = Math.max(-1, Math.min(1, bytes[i]));
						let val = s < 0 ? s * 0x8000 : s * 0x7FFF;
						val = parseInt(255 / (65535 / (val + 32768)));
						data.setInt8(offset, val, true);
					}
				} else {
					for (let i = 0; i < bytes.length; i++, offset += 2) {
						let s = Math.max(-1, Math.min(1, bytes[i]));
						data.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
					}
				}
				return new Blob([data], { type: 'audio/wav' });
			}
		};
	}

	//开始录音
	start () {
		this.audioInput.connect(this.recorder);
		this.recorder.connect(this.context.destination);

		//音频采集
		let self = this;
		this.recorder.onaudioprocess = function (e) {
			self.audioData.input(e.inputBuffer.getChannelData(0));
		};
	};

	//停止
	stop () {
		this.recorder.disconnect();
	};

	//获取音频文件
	getBlob () {
		this.stop();
		return this.audioData.encodeWAV();
	};

	//回放
	play (audio) {
		audio.src = window.URL.createObjectURL(this.getBlob());
	};

	//清理缓存的录音数据
	clear (audio) {
		this.audioData.buffer = [];
		this.audioData.size = 0;
		this.audioData.duration = 0;
		audio.src = ''
	};

	static checkError (e) {
		const { name } = e;
		let errorMsg = ''
		switch (name) {
			case 'AbortError': errorMsg = '录音设备无法被使用'; break;
			case 'NotAllowedError': errorMsg = '用户已禁止网页调用录音设备'; break;
			case 'PermissionDeniedError': errorMsg = '用户已禁止网页调用录音设备'; break;     // 用户拒绝
			case 'NotFoundError': errorMsg = '录音设备未找到'; break;
			case 'DevicesNotFoundError': errorMsg = '录音设备未找到'; break;
			case 'NotReadableError': errorMsg = '录音设备无法使用'; break;
			case 'NotSupportedError': errorMsg = '不支持录音功能'; break;
			case 'MandatoryUnsatisfiedError': errorMsg = '无法发现指定的硬件设备'; break;
			default: errorMsg = '录音调用错误'; break;
		}
		return { error: errorMsg }
	};

	static get (callback, config) {
		if (callback) {
			if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
				navigator.mediaDevices.getUserMedia({ audio: true, video: false }).then((stream) => {
					let rec = new Recorder(stream, config);
					callback(rec);
				}).catch((e) => {
					callback(Recorder.checkError(e));
				})
			} else {
				navigator.getUserMedia({ audio: true, video: false }).then((stream) => {
					let rec = new Recorder(stream, config);
					callback(rec);
				}).catch((e) => {
					// Recorder.checkError(e)
					callback(Recorder.checkError(e));
				})
			}
		}
	};
}